This invention relates to lampholder fittings that are adapted to screw into the Edison base lampholder sockets commonly used for supporting and operating light bulbs in lighting fixtures and portable lamps, and more particularly to the male screw bases that are used to permit the use of fluorescent lampholder fittings and other electrical devices in ordinary incandescent lamp sockets.
There are a number of lampholder fittings currently available which are adapted to fit Edison base lampholders (commonly called female sockets) and to provide both mechanical support and electrical input power for various devices including fluorescent lamp systems. Since most of the devices are substantially larger than the incandescent light bulbs for which the lampholder was originally designed, there is a known safety hazard that may occur from over-torqueing the lampholder fitting into the lampholder. In such cases, the ability to grip a lampholder more firmly than is possible with an ordinary light bulb creates excessive torque to the degree that the lampholder is damaged. Further, an overtightened lampholder fitting tends to freeze in place to the extent that the lampholder may be damaged when the lampholder fitting is unscrewed.
The magnitude of the described problem is great enough that certain safety testing agencies have placed limitations on the type of device that can be installed in an Edison base lampholder.
The object of this invention is to provide a male screw base that cannot apply any excessive torque load on a lampholder, either during installation or removal of the lampholder fitting to which the screw base is attached.